We understand the devastating ecological impacts that feral fish have on wetland ecosystems and can undertake feral fish control with the use of custom made netting, electrofishing, spearfishing and biological control methods.

Feral Fish Control & Native Fish Restocking


The degree of ecological impact depends on the fish species and on a case-by-case basis related to environmental attributes of the water body. There is a consensus among the scientific community that Feral Carp (Cyprinus carpio) is the greatest ecological threat compared to other feral fish (Mosquitofish, Rosy barbs, Swordtails, Catfish) and needs to be eradicated immediately. Feral fish contribute to:

  • Increase turbidity and mobilisation of phosphorus from lake sediment (Benthivorous fish – Carp)
  • Reduce/destroy aquatic macrophyte biomass
  • Reduce macro invertebrate diversity
  • Increase nutrient levels and chance of eutrophication
  • Increase incidence of algal blooms
  • Reduce net recruitment of native fish
  • Increase disease transmission into native fish species
  • Localised extinctions of native fish species

For large feral fish species we use Electrofishing systems and large custom-made seine nets up to 100m long with 5m drop to corner. Our technicians are licensed divers and pursue larger species via spearfishing in areas where netting is not possible. We are also working on the development of biological control methods to aid in the control smaller feral fish such as Mosquitofish, Rosy barbs and Swordtails.

PASES Aqua can also restock lakes and wetlands with native fish including the Western Pygmy Perch (Nannoperca vittata) and the Western Minnow (Galaxias occidentalis).

Some of the work we have done

For the best advice available, please contact our Wetland specialists to discuss your project requirements.